6600-6619 converted in 1955 from 1909 62000-63499 standard gauge box cars. Cars received 4'-8" Andrews trucks from 5900 stock cars.
6400, 6401, 6404, 6407 converted from the same cars in 1957
6620-6694 converted in 1956 from 1909 37000-37499 standard gauge stock cars. The 5900 stock car trucks were also used.
6402, 6403, 6405, 6406 rebuilt from the same cars in 1957